The Martian Mile-Ride Club

Opportunity continues to be in excellent health working inside of "Endurance Crater." The current cycle is to use the deep-sleep mode every second night and to support an early morning Odyssey communications pass on the non-deep-sleep nights.

Opportunity is experiencing very good solar exposure, averaging more than 700 watt-hours per sol available from the solar arrays. Driving to a rock called "Wopmay" has proven to be more challenging than expected, with Opportunity experiencing drive slippage of more than 50 percent in a couple of instances. As Opportunity drove toward Wopmay, it encountered a hidden obstacle: a rock buried under the sand that resulted in 100 percent slip for a good part of the traverse.

Rover planners estimated that, at the end of the traverse, Opportunity was within 30 centimeters (just under one foot) of Wopmay, uncomfortably close!

The rover has spent over four months traversing these kinds of steep slopes inside Endurance Crater. Opportunity spent its first night inside Endurance on sol 134. To date, the rover has spent 130 sols in the crater, grinding 21 targets with the rock abrasion tool, performing 62 integrations with the Mössbauer spectrometer and 33 with the alpha particle X-ray spectrometer, and taking 115 observations with the miniature thermal emission spectrometer. Opportunity finally completed observations on the rock "Wopmay," and is ready to begin its trek towards "Burns Cliff" on the way to exiting Endurance Crater.

For sol 263, a decision was made to delete the panoramic camera imagery without downlinking it, since on board memory was tight and the mission team already had complete coverage of the part of Wopmay captured.

Total odometry after sol 264 is 1,638.57 meters (1.0181 mile).

On the other side of the planet, the earlier-to-arrive Spirit rover had long exceeded its own record driving distance. There is some evidence of road wear on the rover, not only with its catching sixth wheel that needs lubrication, but also with newer steering issues that appear to be unrelated. Engineering tests have shown that while a particular electronics relay in question is still functional, it does appear to operate only intermittently.

For mission planners, this kind of intermittency complicates driving–even more than an outright mechanical breakage. While a breakage can be planned around or calibrated against, the "sometimes good, sometimes bad" nature of the steering translates into unknown final coordinates for preplanned drives. The root cause of the failed relay command is under investigation. Engineers will continue to drive, but will steer the rover in a tank-like fashion, not using the steering actuator in question.

Spirit is otherwise healthy and is in a safe location. After working on Mars for three times as long as its primary three-month mission, Spirit is currently investigating the rocks near the Columbia Hills.

Since the Sun moves low across the northern sky over Gusev Crater at this time of year, rover planners are attempting to keep the solar panels tilted toward the north. Spirit has driven a total of 3,641 meters (about 2.3 miles) since landing nine months ago.